I've an iceQR sticker on my helmet given away at a Sussex Police stand at a vintage vehicle show. It is used nationwide and the police and ambulance crews know to look for it.
It costs 99p a year to renew and you can enter all the personal info you want on the database.
Next of kin
Medical history (relevant)
Doctors contact number
Driving licence number
National health number
Photos of the user, carer or guardian etc.
Any other useful information.
Unfortunately the service for new participants is paused during the virus prob but will resume.